High-quality lubricating oils are critical for the operation of modern machinery and automobiles. Unfortunately, the supply of natural crude oils having good lubricating properties is not adequate for present demands. Due to uncertainties in world crude oil supplies, high-quality lubricating oils must be produced from ordinary crude feedstocks.
Numerous processes have been proposed for producing lubricating oils that can be converted into other products by upgrading the ordinary and low-quality stocks.
It is desirable to upgrade a crude fraction otherwise unsuitable for lubricant manufacture into one from which good yields of lube oils can be obtained.
Normal alphaolefins boiling in the lube oil range, in general C.sub.20 +, have very high pour points and therefore are unsuitable for use as lube oils. It is known that low pour point oils can be made by polymerization of C.sub.10 - normal alphaolefins to polyalphaolefin oils.
The production of polyalphaolefin lube oils, however, is limited because polyalphaolefins made with C.sub.12 + normal alphaolefins have high pour points compared to polyalphaolefins made with C.sub.10 - normal alphaolefins. Polyalphaolefins have several valuable properties such as low viscosities at low temperatures which improves cold engine starting, reduces friction and increases fuel efficiency, high viscosity indexes and high thermal stability and oxidation resistance which prevents the buildup of sludge, and a high boiling range for its viscosity which minimizes evaporative loss. Up to now, production has been limited because no process has been developed to convert high pour point normal alphaolefins and polyalphaolefins to low pour point lube oils in high yield.
Normal alphaolefins and polyalphaolefins are very expensive starting materials. Isomerization processes are known in the art that are useful to lower the pour point of waxy feeds. However, because the selectivity of such processes is not high, they are unsuitable for use with expensive feeds such as olefinic feeds.